008
FXUS65 KBYZ 261854
AFDBYZ
AREA FORECAST DISCUSSION
NATIONAL WEATHER SERVICE BILLINGS MT
1254 PM MDT FRI JUN 26 2026
KEY MESSAGES
- SEVERE THUNDERSTORMS COULD IMPACT MUCH OF THE AREA TODAY AND
SATURDAY, AND EASTERN MT ON SUNDAY. MAIN HAZARDS ARE LARGE HAIL
AND STRONG WIND GUSTS.
- STORMS WILL ALSO BE CAPABLE OF PRODUCING HEAVY RAINFALL TODAY
AND SATURDAY.
- SNOW IS LIKELY IN THE MOUNTAINS ABOVE 8300 FEET SATURDAY NIGHT
INTO SUNDAY NIGHT, WITH ACCUMULATIONS OF 1-2".
- WARMING AND DRYING TREND NEXT WEEK.
DISCUSSION
THROUGH NEXT FRIDAY...
MAIN WEATHER CONCERN TODAY THROUGH SUNDAY IS SEVERE WEATHER. LOW-
LEVEL SOUTHEASTERLY FLOW TODAY IS BRINGING WARM AND MOIST AIR INTO
OUR AREA WITH DEWPOINTS IN THE 50S. SURFACE HEATING IS OCCURRING
TO VARYING DEGREES ACROSS OUR AREA WITH NORTHEASTERN AREAS HAVING
MORE SUNSHINE AND MIXED CLOUDS AND SUN OVER THE REST OF THE AREA.
RAP SUGGESTS THAT MUCAPE CAN APPROACH 1000-1700 J/KG THIS
AFTERNOON LARGELY FROM THE SURFACE HEATING AND LOW LEVEL
MOISTURE. AT THE SAME TIME, A 500 MB LOW APPROACHING FROM THE WEST
WILL BRING INCREASED WIND SPEEDS ALOFT AND THUS WIND SHEAR OVER
OUR AREA. 12Z HREF SUGGESTS THAT STORMS SHOULD FORM OVER THE
HIGHER TERRAIN EARLY THIS AFTERNOON THEN MOVE NORTHEASTWARD OVER
THE LOWER ELEVATIONS INTO THIS EVENING. ENVIRONMENT SHOULD
SUPPORT SUPERCELLS AND STORM CLUSTERS. SPC HAS OUR ENTIRE
FORECAST AREA IN AT LEAST A MARGINAL RISK (1/5) AND THE
NORTHEASTERN 2/3 OF THE FORECAST AREA IN A SLIGHT RISK (2/5). MAIN
HAZARDS ARE LARGE HAIL AND STRONG WIND GUSTS, THOUGH THERE IS
ALSO A LOW CHANCE OF A TORNADO IN CENTRAL MT. PLEASE BE WEATHER
AWARE THIS AFTERNOON-EVENING AND HAVE MULTIPLE WAYS TO RECEIVE
WARNINGS.
SATURDAY BRINGS ANOTHER ROUND OF POTENTIAL SEVERE WEATHER TO OUR
FORECAST AREA. AS THE 500 MB FLOW MOVES CLOSER TO OUR AREA,
TEMPERATURES ALOFT WILL COOL, WHILE A SURFACE LOW SOMEWHERE IN THE
SE MT/NE WY/NW SD AREA WILL HELP BRING LOW-LEVEL MOIST AIR INTO
OUR AREA. THESE FACTORS SHOULD SUPPORT INCREASED INSTABILITY WITH
12Z HREF SHOWING MUCAPE GREATER THAN 1000 J/KG EAST OF BILLINGS.
THE INSTABILITY COMBINED WITH SHEAR OF 40-50 KT SHOULD SUPPORT
ORGANIZED SEVERE CONVECTION WITH 12Z HREF SHOWING SEVERAL HELICITY
TRACKS EMERGING FROM THE BEARTOOTH/ABSAROKA AND BIGHORN MOUNTAINS
THEN TRACKING NORTHEASTWARD. THE STORMS COULD EVOLVE FROM
INDIVIDUAL CELLS TO A MORE LINEAR FEATURE. SPC HAS HIGHLIGHTED A
SEVERE WEATHER RISK RANGING FROM MARGINAL (1/5) OVER WESTERN AREAS
TO ENHANCED (3/5) OVER EASTERN AREAS WITH PEAK GUSTS OF 74 MPH
POSSIBLE OVER EASTERN MT AND LARGEST HAIL GREATER THAN 2 INCHES IN
DIAMETER EAST FROM SHERIDAN COUNTY, WY NORTH AND EASTWARD.
FOR TODAY AND SATURDAY, HEAVY RAIN RATES ARE POSSIBLE WITH
PRECIPITABLE WATER VALUES NEAR OR OVER 1 INCH. 12Z HREF SHOWS THAT
A FEW ISOLATED POCKETS OF 1-3" OF RAIN ARE POSSIBLE TODAY. FOR
SATURDAY A FEW ISOLATED POCKETS OF ABOUT 1-2" OF RAIN ARE
POSSIBLE.
ON SUNDAY, THE 500 MB LOW WILL BE OVER MT WITH LOW-LEVEL WESTERLY
WINDS OVER MOST OF THE AREA. THIS PATTERN SHOULD PRODUCE SCATTERED
SHOWERS AND THUNDERSTORMS BUT ANY SEVERE WEATHER SHOULD BE
CONFINED TO EASTERN MT WHERE THEY LOOK TO HAVE WARMER AND
RELATIVELY MORE HUMID CONDITIONS. BECAUSE OF THIS SPC HAS EASTERN
MT IN A MARGINAL RISK (1/5) FOR SEVERE WEATHER ON SUNDAY WITH THE
MAIN HAZARDS BEING HAIL AND WIND.
COOLER AIR WILL LOWER SNOW LEVELS FOR OUR MOUNTAIN AREAS SATURDAY
NIGHT INTO SUNDAY NIGHT, WITH LIGHT SNOW ABOVE 8300 FEET OR SO.
ACCUMULATION COULD REACH 1-2" ABOVE THE SNOW LEVEL.
ON MONDAY, 500 MB LOW WILL SLOWLY MOVE INTO SOUTH CENTRAL CANADA
AND WEAKEN. OUR FORECAST AREA WILL BE UNDER CYCLONIC FLOW IN
A COOLER AIR MASS WITH LESS LOW LEVEL MOISTURE AVAILABLE TO WORK
WITH. THIS IS A RECIPE FOR MOSTLY CLOUDY SKIES WITH SCATTERED
SHOWERS AND GENERAL THUNDERSTORMS, BUT WITH LESS INSTABILITY WE
ARE NOT EXPECTING SEVERE WEATHER AT THIS TIME.
FOR TUESDAY-FRIDAY, CONDITIONS WILL TREND WARMER AS THE 500 MB LOW
MOVES FARTHER AWAY FROM MT, THE 500 MB FLOW BECOMES SOUTHWESTERLY
AND HEIGHTS BUILD OVER OUR FORECAST AREA. THE SOUTHWESTERLY FLOW
PATTERN SUPPORTS PERIODS OF SCATTERED SHOWERS AND THUNDERSTORMS
(ABOUT 20-40% CHANCE) MOST DAYS. ECMWF ENSEMBLES SUGGEST THAT
INSTABILITY SHOULD BE LOW TUESDAY AND WEDNESDAY BEFORE IT STARTS
TO INCREASE AGAIN LATER IN THE WEEK WITH INCREASING LOW LEVEL
WARMTH. GIVEN THIS, THERE DOES NOT APPEAR TO BE A SEVERE WEATHER
RISK UNTIL LATER NEXT WEEK, PERHAPS THURSDAY AND ON. RMS
AVIATION
MID TO HIGH CLOUD COVER REMAINS OVER MUCH OF THE AREA, THOUGH
TERMINALS EAST OF KBIL HAVE BEGUN TO SEE CLEARING. SHOWERS AND
THUNDERSTORMS ARE FORECAST TO DEVELOP THIS AFTERNOON FROM THE
SOUTHWEST AND MOVE NORTHEAST THROUGH THE EVENING. A FEW
THUNDERSTORMS COULD BE STRONG TO SEVERE, CAPABLE OF PRODUCING
LARGE HAIL, STRONG WIND GUSTS OVER 50 KNOTS, AND HEAVY RAINFALL.
IFR CONDITIONS ARE POSSIBLE UNDER HEAVIER STORMS. LOOK FOR
CONVECTION TO DIMINISH THROUGH 06Z. WINDS WILL SHIFT TO THE NORTH
TONIGHT WITH A COLD FRONTAL PASSAGE.
THUNDERSTORM TIMING FOR SITES:
KLVM: 18Z-06Z
KBIL: 21Z-04Z
KSHR: 20Z-03Z
KMLS: 00Z-04Z
MATOS
PRELIMINARY POINT TEMP/POPS
SAT SUN MON TUE WED THU FRI
-----------------------------------------------------------
BIL 059/075 052/071 050/069 052/078 054/084 057/088 059/092
58/T 82/T 25/T 21/B 11/U 10/U 02/T
LVM 050/069 043/062 040/059 041/072 045/078 047/083 050/086
47/T 96/T 68/T 42/T 23/T 21/U 02/T
HDN 058/078 050/074 049/073 050/080 051/086 054/090 057/094
67/T 63/T 44/W 21/B 11/U 10/U 01/U
MLS 061/081 054/075 052/073 052/079 054/086 058/090 061/093
45/T 83/W 54/T 21/B 11/U 11/U 01/U
4BQ 061/081 054/077 053/075 052/080 055/087 058/092 061/095
56/T 51/U 43/W 11/U 11/U 11/U 01/U
BHK 059/086 052/077 051/075 049/078 052/085 055/090 058/092
43/T 71/U 64/T 21/U 11/U 11/U 12/T
SHR 054/076 047/072 045/072 045/077 047/084 051/088 054/092
36/T 53/T 52/W 11/U 11/U 11/U 01/U
BYZ WATCHES/WARNINGS/ADVISORIES
MT...NONE.
WY...NONE.
WEATHER.GOV/BILLINGS
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